Urinary iodine concentration after household use of iodine-fortified bouillon among women of reproductive age and preschool children in northern Ghana: A secondary analysis of the CoMIT trial

Background: Monitoring urinary iodine concentration (UIC) after sustained exposure informs iodine delivery strategies. We aimed to compare endline UIC among women of reproductive age (WRA) and preschool children (PSC) receiving multiple micronutrient-fortified (MMF) vs. iodine-only bouillon, and to describe population iodine status at baseline and endline. Methods: This pre-specified secondary outcome analysis used Condiment Micronutrient Innovation Trial (CoMIT) data. Non-pregnant, non-lactating WRA (15-49 years) and PSC (2-5 years) were enrolled at the household level. Households received MMF or iodine-only bouillon for 9 months (38 weeks); both contained iodine (KIO3) at 30 ug/g. Baseline and endline UIC (ug/L) were measured by modified Sandell-Kolthoff reaction in spot urine samples. ANCOVA models, adjusted for baseline log-UIC and recruitment site, compared endline geometric mean UIC between trial arms. Median UIC at both timepoints was compared to WHO cut-offs (ug/L): <100 (insufficient), 100-199 (adequate), 200-299 (above requirements), and >=300 (excessive); the prevalence of UIC <50 ug/L was calculated. Results: Endline UIC data were available for 611 WRA and 630 PSC. Adjusted endline UIC did not differ by arm (geometric mean ratio [95% CI]: WRA 0.97 [0.86-1.10]; PSC 0.96 [0.84-1.10]). With arms combined, median UIC increased among WRA (100.5 to 124.6 ug/L) and PSC (109.6 to 136.9 ug/L), with fewer samples <50 ug/L at endline. Conclusions: Adjusted endline UIC did not differ between trial arms. After 9 months' use of iodine-fortified bouillon, median UIC remained adequate among WRA and PSC, with fewer samples <50 ug/L at endline.